Experimental medicine approaches to drug development in anxiety disorders

Numerous pharmacological and psychological approaches are efficacious in patients with generalized anxiety disorder (GAD) and social anxiety disorder (SAD), though some patients do not respond to treatment and others relapse despite continuing with interventions that were initially beneficial. Other patients respond but stop treatment because of unwanted effects including sexual dysfunction, emotional blunting and weight gain. There is much need for novel interventions with greater overall effectiveness and enhanced acceptability when compared to current treatments, or with particular effectiveness in specific patient groups. ‘Experimental medicine’ studies conducted in healthy subjects provide a ‘proof-of-concept’ approach for determining whether to progress to pivotal efficacy studies, thereby potentially reducing delays in translating innovations into clinical practice. Examples of such studies include inhalation of air ‘enriched’ with 7.5% carbon dioxide, which mirrors the subjective, autonomic and cognitive features of GAD, and administration of testosterone or oxytocin, which respectively target the social avoidance and emotion processing biases of SAD.